1. Field of the Invention
The present invention relates to a recording apparatus for recording images on a recording medium by using recording means while supporting the recording medium in a recording area.
2. Description of the Related Art
Conventionally, a recording apparatus for recording on a recording medium by using recording means, such as a recording head, has been provided with a conveyor roller located upstream of a recording position of the recording head as viewed in the direction of conveyance of the recording medium, and a press-contact member pressed into contact with the conveyor roller so that the recording medium is nipped and conveyed by the press-contact member and the conveyor roller. And, the position of the conveyor roller is fixed, while the press-contact member is rockably pressed into contact with the conveyor roller. That is, the position of the surface of the recording medium conveyed by the conveyor roller is always fixed, and a surface of the press-contact member with respect to the recording medium is rocked.
Therefore, when the thickness of the recording medium is changed, the distance between the recording head and the recording surface of the recording medium is changed. In the case of a thick recording medium, such as an envelope, as compared with a thin recording medium, such as a cut paper, the distance between the recording head and the recording surface of the recording medium becomes a short distance so that recording quality may be changed and the recording medium may be caught by a carriage when a main scanning is performed with the cartridge.
Thus, a mechanism for maintaining the recording head and the recording surface of the recording medium at a constant distance as shown in FIGS. 8 and 9 has been conventionally introduced. FIG. 8 is a sectional view taken along a plane perpendicular to a main scanning direction of a so-called serial-type printer in which the recording head scans in the main scanning direction; and FIG. 9 is a partial view of the carriage viewed from the direction of arrow A as shown in FIG. 8.
Referring to these drawings, there are shown a carriage 101 having a recording head and scanning in the main scanning direction, a carriage shaft 102, a roller 103, a roller lever 104 holding the roller 103, a rail 105 provided parallel to the carriage shaft 102, a conveyor roller 106 for conveying the recording medium, a press-contact member 107 for pressing the recording medium into contact with the conveyor roller 106 to generate a conveying force, and a spring 108 provided between the roller lever 104 and the carriage 101.
By the action of the spring 108, the roller lever 104 and the roller 103 are pressed against the rail 105. By the reaction thereof, the carriage 101 receives a force of rotating clockwise in FIG. 8 about the carriage shaft 102. The carriage 101 is provided with a projection 101a, and the projection 101a is always kept in contact with the press-contact member 107 by the rotating force of the carriage 101 toward the press-contact member 107. For this reason, the recording head (not shown) mounted on the carriage 101 and the press-contact member 107 are always maintained at not less than the constant distance.
Therefore, since between the recording surface of the recording medium and the carriage 101, and further, the recording head are always maintained at not less than the constant distance even if the thickness of the recording medium is changed, the main scanning is always performed with the carriage 101 because the recording medium is not caught by the carriage 101.
However, in the conventional recording apparatus as described above, the distance between the carriage 101 rotating about the carriage shaft 102 and the press-contact member 107 is maintained by means of the projection 101a provided on the carriage 101. Thus, a rotation amount of the carriage 101 rotating counterclockwise in FIG. 8 about the carriage shaft 102 is changed when the thickness of the recording medium is changed. For this reason, the angle of the carriage 101, and the angle of the recording head with respect to the recording surface of the recording medium are changed although the amount of change is slight. Therefore, although a change in the thickness of the recording medium does not substantially affect recording to a recording medium of the same thickness, the recording position of the recording head with respect to the recording medium is slightly changed in accordance with the change of the thickness of the recording medium.
In addition, since the position of the projection 101a is closer to the carriage shaft 102 than the recording position of the recording head, variations in the length of the projection 101a are expanded so as to appear as variations in the distance between the recording head and the recording surface. For this reason, a predetermined distance between the recording head and the recording surface might be changed for each apparatus to vary recording quality for each apparatus.
Further, in order to maintain the predetermined distance between the recording head and the recording surface for the purpose of avoiding the above variations, the length of the projection 101a must be carefully managed. This leads to an increase in cost of the apparatus.
Still further, since the projection 101a is always pressed into contact with the holding member, it is worn out by friction when the main scanning of the carriage is repeated. As a result, the distance between the recording head and the recording surface might be changed during the use thereof for a long period of time.